我目前正在制作一个程序，我可以使用两个充气的edittexts并用它们进行计算。所以我试图获取每个值，将它们放入指定的arraylist并根据相应的数组计算值，但我遇到麻烦，因为我得到一个indexoutofbounds异常，我不知道我的代码是否正常工作。我能得到一些帮助吗？
这是我的代码。
public class CalculateActivity extends AppCompatActivity {
Button calculate;
LinearLayout courses;
ArrayList<Course> coursesList;
SemesterDatabase db;
TextView gpa;
int percentage = 0;
int hundredth =0;
float averageGrade = 0.0f;
float[] gradePoints = new float[]{};
ArrayList<Float> gradesList = new ArrayList();
ArrayList<Float> scoreList = new ArrayList();
ArrayList<Float> totalList = new ArrayList();
int id;
TextView semester;
class C03171 implements OnClickListener {
C03171() {
}
public void onClick(View view) {
float gradePointsCalc = 0.0f;
float totalCrdtHrs = 0.0f;
//编辑Jyoti JK，谢谢你的帮助
for (int x = 0; x < scoreList.size()&& x<totalList.size(); x++)
{CalculateActivity.this.gradesList.add(scoreList.get(x) / totalList.get(x));
}
for (int i = 0; i < CalculateActivity.this.coursesList.size(); i++) {
int crdtHrs = ((Course) CalculateActivity.this.coursesList.get(i)).getCreditHours();
totalCrdtHrs += (float) crdtHrs;
averageGrade += (((Float)CalculateActivity.this.gradesList.get(i).floatValue())*(((Course) CalculateActivity.this.coursesList.get(i)).getCreditHours())/totalCrdtHrs);
}
float gpaCalc = averageGrade;
CalculateActivity.this.gpa.setText(String.format("%.3f", new Object[]{Float.valueOf(gpaCalc)}));
}
}
class C03194 implements DialogInterface.OnClickListener {
C03194() {
}
public void onClick(DialogInterface dialogInterface, int i) {
dialogInterface.cancel();
}
}
class C03205 implements DialogInterface.OnClickListener {
C03205() {
}
public void onClick(DialogInterface dialogInterface, int i) {
CalculateActivity.this.db.deleteSemester(CalculateActivity.this.id);
CalculateActivity.this.db.deleteAllCourses(CalculateActivity.this.id);
CalculateActivity.this.onBackPressed();
}
}
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView((int) R.layout.activity_calculate);
setSupportActionBar((Toolbar) findViewById( R.id.toolbar));
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setTitle((CharSequence) "Calculate GPA");
this.db = new SemesterDatabase(this);
this.id = getIntent().getIntExtra("semesterId", 1);
this.coursesList = this.db.getAllCourses(this.id);
this.semester = (TextView) findViewById(R.id.semester);
this.semester.setText(getIntent().getStringExtra("semesterName"));
this.gpa = (TextView) findViewById(R.id.gpa);
this.calculate = (Button) findViewById(R.id.calculate);
this.courses = (LinearLayout) findViewById(R.id.courses);
addCourses();
this.calculate.setOnClickListener(new C03171());
}
public void addCourses() {
LayoutInflater inflater = LayoutInflater.from(this);
for (int i = 0; i < this.coursesList.size(); i++) {
View v = inflater.inflate(R.layout.item_course, null, false);
this.courses.addView(v);
final int position = CalculateActivity.this.scoreList.size();
final int position2 = CalculateActivity.this.totalList.size();
CalculateActivity.this.scoreList.add(0.0f);
final EditText Score = (EditText) v.findViewById(R.id.Score);
final EditText Total = (EditText) v.findViewById(R.id.Total);
Score.addTextChangedListener(new TextWatcher() {
public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
}
public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
}
public void afterTextChanged(Editable editable) {
percentage = Integer.parseInt(editable.toString());
float perc = (float) percentage;
CalculateActivity.this.scoreList.set(position, perc);
}
});
Total.addTextChangedListener(new TextWatcher() {
public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
}
public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
}
public void afterTextChanged(Editable editable) {
hundredth = Integer.parseInt(editable.toString());
float hund = (float) percentage;
CalculateActivity.this.scoreList.set(position, hund);
}
});
}
}
基本上我认为我的代码正在做的是从
获取edittext值 Score.addTextChangedListener(new TextWatcher() {
public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
}
public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
}
public void afterTextChanged(Editable editable) {
percentage = Integer.parseInt(editable.toString());
float perc = (float) percentage;
CalculateActivity.this.scoreList.set(position, perc);
}
});
Total.addTextChangedListener(new TextWatcher() {
public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {
}
public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {
}
public void afterTextChanged(Editable editable) {
hundredth = Integer.parseInt(editable.toString());
float hund = (float) percentage;
CalculateActivity.this.scoreList.set(position, hund);
}
});
获取值
for (int x = 0; x < scoreList.size(); x++)
{
ArrayList<Float> finalscore = new ArrayList();
finalscore.add(scoreList.get(x) / totalList.get(x));
for (int j = 0; j < finalscore.size(); j++)
{
CalculateActivity.this.gradesList.add(finalscore.get(j));
}
}
最后使用
计算它 for (int i = 0; i < CalculateActivity.this.coursesList.size(); i++) {
averageGrade += ((Float)CalculateActivity.this.gradesList.get(i).floatValue())*(((Course) CalculateActivity.this.coursesList.get(i)).getCreditHours());
}
float gpaCalc = averageGrade;
CalculateActivity.this.gpa.setText(String.format("%.3f", new Object[]{Float.valueOf(gpaCalc)}));
但我绝对不知道哪里出错了，我不知道怎么看错了。我希望得到详细的评论！
哦，这是错误日志。
FATAL EXCEPTION: main
Process: com.example.joon.chadwickgrades, PID: 19395
java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
at java.util.ArrayList.get(ArrayList.java:411)
at com.example.joon.chadwickgrades.CalculateActivity$C03171.onClick(CalculateActivity.java:66)
at android.view.View.performClick(View.java:5623)
at android.view.View$PerformClick.run(View.java:22433)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6247)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:872)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:762)
答案 0 :(得分：0)
作为您的代码，
for (int x = 0; x < scoreList.size(); x++)
{
ArrayList<Float> finalscore = new ArrayList();
finalscore.add(scoreList.get(x) / totalList.get(x));
for (int j = 0; j < finalscore.size(); j++)
{
CalculateActivity.this.gradesList.add(finalscore.get(j));
}
}
对于每次迭代，
1.您正在创建一个finalscore arraylist对象。
2.只添加一个元素。
3.然后内部for循环开始。 finalscore的大小总是一个。并且您将它添加到等级列表。
我认为你可以改变它，
for (int x = 0; x < scoreList.size() && x<totalList.size(); x++)
{
CalculateActivity.this.gradesList.add(scoreList.get(x) / totalList.get(x));
}
并更改代码，
for (int i = 0; i < CalculateActivity.this.coursesList.size() && i <CalculateActivity.this.gradesList.size(); i++) {
int crdtHrs = ((Course) CalculateActivity.this.coursesList.get(i)).getCreditHours();
totalCrdtHrs += (float) crdtHrs;
averageGrade += (((Float)CalculateActivity.this.gradesList.get(i).floatValue())*(((Course) CalculateActivity.this.coursesList.get(i)).getCreditHours())/totalCrdtHrs);
}
修改
关键是，每当您从列表中获取数据时，您需要检查它是否为空以及它的大小。这是避免异常的最佳做法